DESCRIPTION (Adapted from the applicant's description): Neuropathic pain conditions in adults, including diabetic neuropathy, post-surgical and post-traumatic neuropathies and AIDS-associated neuropathy, produce considerable suffering and disability. Neuropathic pain in children has previously received comparatively less formal study. The Pain Treatment Service at Children's Hospital in Boston has become a referral center for children with many types of neuropathic pain, but especially limb pain associated with signs of abnormal circulation, which has been variously named reflex sympathetic [or neurovascular] dystrophy [RSD/RND], sympathetically maintained pain [SMP], and complex regional pain syndrome type 1 [CRPS1]. Over the past 10 years, >450 children and adolescents with RSD have been treated at the hospital. In 1992, the investigators reported on 2-5 year follow-up of their first 70 patients, and found that: [1] females outnumbered males 6:1, [2] lower extremities were affected five times as often as upper extremities, [3] many patients sustained trauma or overuse injuries in sports, ballet and gymnastics, [4] school absenteeism was extensive, [5] at presentation, most were confined to crutches or wheelchairs [6] >50 percent had resolution of pain and recovery of function with treatment that emphasized active physical therapy, cognitive-behavioral treatments, and family/lifestyle interventions and patient/parent education. The previous studies are limited by retrospective design and by absence of precise measures of motor, sensory, automatic and psychosocial function. In this project, the investigators propose to study pediatric patients with RSD with outcomes measures including: [1] motor functioning, [2] sensory disturbances, including thresholds, [3] cardiac and peripheral autonomic control, and [4] psychosocial functioning, including school attendance/performance. In a randomized prospective trial, we will compare the effectiveness and efficiency of two physical therapy regimens [once per week vs. three times per week]. For patients with persistent disability and pain refractory to our rehabilitative approach, we also propose a clinical trial and paradigm for objectively evaluating responses to sympathetic blockade. The long-range aim is to better understand the causes, exacerbating factors, and determinants of responses to treatment of children with RSD/CRPS].